The Calne Girls' Association dates back to the time of Miss Florence Dyas, who as Headmistress between 1888 and 1911, set up the original Guild of St Mary's in 1891. This then became The Old Girls' Association, and by 2010 was rebranded The Calne Girls' Association in a bid to update both the name and the style of the newsletter!

Today the CGA has over 3,500 members worldwide, ranging from Gold Medallist Olympians to award-winning writers, scientists, doctors, artists and actresses. Being a member of the CGA gives old girls the chance to become life members of an exclusive worldwide network. Whilst the CGA ensures that old girls keep in touch with each other, it also acts as an important networking tool, offering advice, mentoring, work experience, careers, travel and social opportunities.

Old girls are invited to come back into school regularly, to meet with and talk to current students to regale them with stories of their outstanding achievements, high flying careers, and life experiences. Reunions are hosted throughout the year for all ages, both in school and at national venues. A Calne girl is a Calne girl for life.